ACTINOMYCES : ACTINOMYCOSIS 341
yellowish granules. This condition, he termed " actinomycosis ".
In cattle the lesions are frequently confined to the jaw and soft
parts of the head and neck.
In man actinomycotic lesions are usually situated in one of
three regions—head and neck, the thorax or the abdomen. The
mouth is a common primary site. The mortality rate varies with
the site of infection ; facial lesions are usually less fatal than the
other types. A chronic abscess with marked proliferation of the
connective tissue forms and spreads locally by direct extension ;
the infection later may generalize by way of the lymphatic or
blood-streams ; the lymph glands are, however, seldom attacked.
Thick viscid pus containing the yellowish " sulphur " granules
is usually discharged from the broken-down central portion.
The epidemiology and pathogenesis of the disease are unknown.
The source of infection has not been determined, but it is ulti-
mately the saliva and nasal discharges of cases, probably animal.
It is, however, frequently impossible to trace a human infection
to an animal source, and there is no evidence that the disease is
contagious in man. Carriers may possibly be responsible for
the transmission of the infection in many cases ; supporting this
theory is the fact that organisms closely resembling A. bovis
have been isolated from the alimentary tract of healthy
individuals. It was at one time considered that infection was
transmitted by the agency of grasses and cereals, but the evidence
supporting this theory is unconvincing. It has never been proved
that A. boms is able to survive outside the animal tissues for any
appreciable time ; moreover, the organism, which some workers
isolated from grass and cereals and considered to be responsible
for the condition, has been found to be a harmless saprophyte
and not A. bovis. While the method of transmission is uncertain,
it appears probable that the infectivity for man of A. boms is
slight and that some predisposing factor, such as trauma, is
necessary to enable infection to take place.
Diagnosis. Examination should be made for the presence of
the ** sulphur " granules in the thick pus ; on rolling the tube
containing the pus the granules usually adhere to the sides and
can be readily detected. The granules are removed and examined,
stained and unstained, after crushing; they are generally soft
and can be crushed without difficulty. The interlacing Gram-
positive mycelia with Gram-negative clubs are seen.
Cultures should be prepared from the granules after they
have been washed in sterile saline. A useful method is the